(I'm confused by your comment Techneut, I'm not the original poster though you quote me)
You love a few bars of this great work, and find the rest deadly boring.
Well, my bad for exagerating ! Actually, I like that sonata, which is amongst my favorites (it really moves me) ; however, if you know it, the first two minutes of the third movement are actually (to me, again) more akin to Czerny than Glazunov. My musical analysis skills are really low, so this might explain that ; I understand that those first two minutes are preparing you for the climax, but sadly I feel Glazunov could have used some more variety (I also don't like the chordal accompagnement, probably a matter of taste on that one) without detracting from the climax. I like small details, and I feel the beginning of this particular movement lacks them. I'm not seeking war though, Glazunov's first sonata is wonderful regardless.
Anyway that was mostly an example of a work I wouldn't undertake because I know I'd want to "skip to the good parts", and find not playing a work in its entirety quite lame. At least not undertake yet, meaning, I'll probably be back when I understand it better (or when the "boring" parts become trivial to learn. Right now it would take a lot of time my enjoyement could use better, I guess ; like "it's okay but I'd rather do something else").
Looking back on my advice, "pick works you like in their whole", it can be so tricky sometimes. My favorite parts when playing are rarely those I liked when listening, so in the end I can often only find out by playing - more experience needed, maybe !
Without patience and endurance, stay well away from this music.
Obviously those are two qualities you'll need on the piano ; but you can be patient yet be frustrated : let me give you an exemple : the moonlight sonata first movement ; some people play it so slowly (and I mean really slowly), and I just can't, independantly of my interpretation of the piece. It just bores me to death (it is so frustrating, not even mentionning it hides some voices), while I love the work at a brisk tempo.
To extrapolate to my comment on Glazunov, it would be the same ; I'd love playing the third movement, but I would dread the opening because I'd have to leash myself not to hurry / truncate it (or maybe not, since I do not know the work ; so I'm more talking about my experience of it as a listener).
Keep in mind my comments applies to works you find challeging to learn, or you are playing for your own pleasure ; when performing for an audience, a work is hardly boring, even if it's only because of the incredible pressure (and anyway I'm usually so adrenaline-full that I can't get bored). I have the "bad" learning method of doing a lot of repetitions (mainly because it's how I memorize and hear things), so I will hear a piece quite a lot before being able to perform it correctly. Even the pieces that make me drool WILL bore me at some point, because I'll have played them so SO many times. Boredom (or maybe my word isn't well chosen, maybe it is more of monotony I am talking ?) will fade with time though, and has nothing to do with music ; it is merely the way I, at least, function as a human being ; I like shiny new things, whether those are harmonies or technical difficulties (hard passages are never boring to me, because they require you to be all ready). I know that when I teach (or learn, all the same), I give my students many different ideas on the same topic (like you know, illustrating that grammar point with several sentences from different texts), to provide them with variety that will hopefully spark interest, that will in turn trigger results.
Also, I think naming virtues makes them quite hollow ; patience can mean so many things, and while one easily understand what meaning you are refering to, using such word quickly points huge character flaws, regardless of your intention. In fact, I think sitting five hours a day behind a piano keyboard, not every single of which you deeply enjoy, automatically brands you as patient ! (on a side note, learning piano as an adult requires so much patience it can be scary ; learning as a kid is much easier because you don't think about it ; now, I just ask myself, "am I working correctly ? Am I efficient ? Will it be ok with time or do I need to work more on that ?)
You say that music is the thing for you (because I wondered about that), and yet you can't seem to find any music that does not bore you.
I dont think that was directed specifically toward me, but I think that is one of the problem with boredom. Sometimes, music is not THE thing for you, it's something you like amongst many other things ; I don't know what composer / musician said that you either have to dedicate yourself to the piano or forget it, but I think this is utmostly untrue. Of course some level of "virtuoso" technique is required to be able to do what you want with the instrument, but I don't think you have to forfeit your life to obtain it (though you will never be able to play the end of the hungarian rhapsody correctly unless you have the shiniest gift ever, remember kids). And most likely, if you've been playing for a few years seriously, playing the piano is A thing for you, because you've invested, are investing, and plan to invest a lot of time in it. To make an analogy, if you want to learn Japanese, you'll have to learn how to write it, that means learning all those ugly little signs and weird figures, though it's a lot of (boring) work ; you'll have to get acquainted to the culture as well ; however, you don't have to become Japanese, just have one as your objective and it'll be fine.
Like in all things however, there are days with and without ; moments with and without. If you're not a professional pianist, you can afford the moments without ; I've made litterature my life, and frankly there are many moments I'm bored with it, so I think it's only natural the same happens with the piano ! I'll dare that analogy, for those that have a significant other, it sometimes might happen that you get bored with him / her ; depending on your morals, beliefs and opportunity, you might act on that boredom or not, but that doesn't change that fact that you are bored...
So rather than say some things, like absolute dedication or boredom, make or make not the pianist, I'd rather try to find ways for the pianist to evolve with these things (hence why I spoke mostly of boredom in my answer to the OP, looking like I was some always-bored person, which is far from the truth !). I mean, how can you be bored when you write so much stuff you have to keep cutting it so it doesn't spill out of the "reply" window ? Maybe when you read it, you tell me...
anger and frustration will not make you a good musician.
I often wonder ! I am for instance a really calm person, but like many "too calm" persons, I have those rage-like moment, those instants of fleeting fury. It can be quite devastating, but it can also be quite inspiring ; you all know those situations when, while speaking, you get so into your subject that the words flow naturally, arguments come by themselves (especially when you are a trained speaker, as you have reflexes you fall back on, organizing your speech without thinking about it for example). I'd venture it can be the same on the piano ; when your technique is lacking, it will be murder ; but when you already "dominate" technically, it will give you excess energy, adrenaline, to fuel your ideas, as long as you keep your cool enough to think about the music (not pounding recklessly). Not unlike playing for strangers !
Abandon the hopes of becoming a Richter, Horowitz, etc. and put away those virtuostic, flashy, technically impossible pieces
Well, I think half the pleasure of learning is trying high, failing, and failing better the next day. You might never reach your goal (I'd quote Kant if I could word it in english !) but it will make you progress. I personally love difficulties, though I might like it easier as years pile upon my back
Also, don't underestimate the pleasure of playing virtuoso and flashy pieces ! Some Scriabin Etudes (though maybe not the hardest Etudes out there, I was humbled to read the Godowsky studies after having learnt a few Chopin originals... I couldn't even sight read it !) give me chills down my spine when playing them. Oh the satisfaction ! It was such a hard work, but finally you can play it. It makes it all worth it. Then you get frustrated because it's not perfect, because you don't have that "Horowitz dynamic" or that "Pletnev tone" or whatever, so you work more, and it gets better. For every second I slam my piano in rage, I know there are several hours of hard work. I'd feel sorry for it if I didn't know I can also make it sound good.
Finally, I never really introduced myself, so let me say, I really talk a lot (that's my job, so it grew into quite the bad habit), and sadly (?) I'd say talking gives me about as much pleasure as piano playing. I try to keep it useful or intelligent, but sometimes it might not be, so feel free to shoot at me when I'm not constructive (I hardly get offended though I might get into it so much as to write more and more). I have a weird sense of humour, but like Juufa said, no malice intended. Especially since I speak english about as much as the next mute lizard.
I like playing the piano, a lot, it is definitly A thing I want in my life. Not having a piano makes me miserable enough to know that. I love listening to recordings here, I discovered many interesting pieces (some of which I love but are probably too boring for me to learn !), so I want to help when I can, and I'd love to post some of my own recordings (soon ? maybe ? but then again, my personality...). I also have many questions I want to ask, but dare not (because I'm shy, really).
(my post was so long I actually had to log back on...)